This invention relates to the use of a propellant power system for propulsion, and more particularly to a system that utilizes aqueous based amine propellant to propel objects, such as satellites, artillery shells; for orbital alignment of objects in space; or with aircraft emergency power units (EPU). This invention may employ a propellant power system that utilizes a method of electrically igniting a propellant such as hydroxylammonium nitrate (HAN) while in a non-catalytic (inert) or catalytic bed.
The EPU is a safety feature utilized in aircraft to quickly provide power in the event of failure of the primary and auxiliary engines. Different types of EPUs exist, such as ram air turbines, engine bleed air driven systems, and propellant power systems.
Propellant power system EPUs generate power from chemical energy from combustion or decomposition reactions that occur within a reaction chamber or catalytic bed. These systems are usually not dependant on aircraft airspeed or on the availability of engine bleed air. An example of a propellant power system EPU is used in the Lockheed-Martin F-16 single engine aircraft. Here, the EPU is up to speed within three seconds, and drives an electric generator and hydraulic pump for up to 10 minutes. It can operate on engine bleed for up to five hours. Typically, for EPU use, a catalytic bed is used about 5 different times before it should be replaced.
The EPU configuration includes a propellant supply system with a fuel injection port, a catalytic bed, a turbine wheel, a gearbox and a gearbox mounted hydraulic pump and electric generator. The propellant supply system stores the propellant until needed, and then delivers the required quantity to the reaction chamber for combustion.
Hydroxylammonium nitrate (HAN), also known as hydroxylamine nitrate, and oxammonium nitrate, has a chemical formula of NH2OH.HNO3 and NH3OH.NO3. This material has been used as a gun propellant, rocket propellant, and as a plutonium recovery agent. HAN is a hygroscopic material generally available in colorless water solutions. It is a byproduct in the fabrication of synthetic fiber. It can also be produced by electrolytic and ion exchange.
Presently, hydrazine may be used as a high-energy rocket propellant and as a reactant in military fuel. Hydrazine has a chemical formula of N2H4. Hydrazine is a highly reactive base and reducing agent.
U.S. Pat. No. 4,777,793 discloses an EPU whereby an igniter creates a spark that ignites a fuel rich ratio of a fuel and air mix to drive a turbine output shaft. This patent discloses a “preferred embodiment of high voltage pulse power” in paragraph 11, line 9. The combustion gas has a temperature of 760° C.-1010° C. (1400° F.-1850° F.). FIG. 5 of the '793 patent illustrates a combustion chamber 251, which may obtain temperatures of 982° C. (1800° F.). The combustion gasses then impinge on turbine 52, as illustrated in FIGS. 1, 3, and 4. This EPU cannot ignite at a cold start, such as when the propellant is around −40° C. (−40° F.). Further, the '793 EPU maintains a flame within the combustion chamber to heat the thermal lining 253 to the combustion temperature, or temperatures of up to 1800° F. (see column 6, line 53). Also, the operation of the unit requires an external source of +28 volts (see column 5, line 43).
U.S. Pat. No. 5,909,001 discloses a method of supplying a high pressure gas pulse to accelerate a firearm bullet. The oxidizer can be liquid HAN used in conjunction with a high voltage pulse power supply and high voltage electrodes. The peak voltage is in the 4 to 20 kilovolt range. The high voltage electrode 20 is illustrated in FIG. 1. FIG. 1 illustrates the high voltage electrode within a fuel mass contained in a housing. The housing is adjacent the bullet. However, this method will not work with low voltage.
U.S. Patent Publication No. 2004/0226280 discloses a high voltage coil coupled to a high voltage conductor, which is coupled to a spark electrode, to decompose a propellant. This publication discloses use of a “high voltage coil 80” in paragraph [0018]. Further, the decomposition chamber should be “hot enough to initiate the reaction (e.g., about 120-130° C. in a vacuum but potentially less with a catalytic bed).” See paragraph [0021]. The spark electrode has an operative distal end disposed outside of a catalytic bed. Low voltage will not trigger the combustion process. See paragraph [0018].
As can be seen, there is a need to: (1) utilize voltage or current to ignite an aqueous based amine propellant; and (2) ignite propellant at cold start, i.e. about −40° C. (−40° F.); without using added technology for thermal ignition, such as exhaust gas, which limits cold ground start utilization, or resistive heating elements, which requires excessive parasitic electric draw, or an open ignition source, such as a spark.